JPH03189456A - Speed change control device for continuously variable transmission - Google Patents

Abstract

PURPOSE:To always change the speed at the same shift speed by changing the control gain of feed-back control in accordance with a degree of deviation between a desired rotational speed and an actual rotational speed of a drive pulley during change of the speed change ratio. CONSTITUTION:A control unit 110 sets a desired rotational speed of a drive pulley in accordance with operating conditions which are detected by various sensors. The feed-back control of the rotational speed of the drive pulley is carried out by a speed change ratio control valve 85 in accordance with a deviation between an actual rotational speed of the drive pulley which is detected by a primary rotational speed sensor 112, and the desired rotational speed. Further, the control gain of the feed-back control is changed in accordance with the degree of the deviation between the desired rotational speed and the actual rotational speed of the drive pulley. Thus, the speed change is made always at the same shift speed during speed change so as to obtain a satisfactory speed change characteristic, and it it possible to prevent hunting of the rotational speed of the drive pulley.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to an improvement in a speed change control device for a continuously variable transmission.

(Prior Art) Conventionally, as a speed change control device for a continuously variable transmission, as disclosed in Japanese Patent Publication No. 63-42146, for example, a driving pulley and a driven pulley each having a variable effective radius,
and a belt wound around between the two pulleys, and supplying hydraulic pressure to or discharging the hydraulic pressure to the hydraulic cylinder of the driving pulley to steplessly adjust the effective radius of both the driving pulley and the driven pulley. It is known that the gear ratio is variably controlled by continuous adjustment.

(Question 8 to be solved by the invention) By the way, as a method of controlling the gear ratio to the target gear ratio,
There is a method of feedback controlling the rotation speed of the drive pulley to its target rotation speed. In other words, first, the target rotation speed of the drive pulley corresponding to the target gear ratio is set according to the operating condition, the actual rotation speed of the drive pulley is detected, and feedback is provided based on the deviation between the actual rotation speed and the target rotation speed. By determining the control amount and using this control amount to control the effective radius of the drive pulley to make the rotation speed the target rotation speed,
・It is of the type that controls the gear ratio to the target gear ratio.

However, it has been found that the shift control device for a continuously variable transmission using the above control method has the following drawbacks. In other words,
As shown in FIG. 10, in a speed change map where the horizontal axis represents the rotation speed and vehicle speed of the driven pulley (secondary pulley) and the vertical axis represents the rotation speed of the drive pulley (primary pulley), the speed change ratio is set to, for example, 0°5-5. 0.7, the driven pulley rotation speed is 5 (loOr, p, I) and the drive pulley rotation speed is 250 (lr, p, *). The deviation from the number 3500 r, p, s is 1o
00r, p, m, and on the other hand, the number of rotations of the driven pulley is 30
00r, p, number of rotations of the pulley driven by the intestine 1500r, p,
When starting the gear shift at point B in the figure of m, the target rotation speed is 21.
00r, p, the deviation from the amount is 600r, p, m,
The deviation of the rotation speed from the target rotation speed varies depending on the rotation speed of the driving pulley and the rotation speed of the driven pulley when changing gears. The above can also be said when the amount of change in the speed ratio is the same at different speed ratios. In other words, change the gear ratio from 1.8 to 2
．． When changing to 0, the amount of change is 0.5-
It is 0.2 as in the case of changing to 0.7, but the above A
When shifting at the 0 point where the driven pulley rotation is 1400r, p, m with the driving pulley rotation speed 250Or, p, m which is the same as the point, the deviation from the target rotation speed 280Or, p, s is 300r, p'', and the rotation speed deviation at the above point A is 1000 r.

p'', and a difference in rotational speed deviation occurs between the two depending on the rotational speed of the driving pulley and the rotational speed of the driven pulley when changing gears. If the rotational speed deviation differs as described above, the feedback control amount is the product of this deviation by the control gain, so even if the gear ratio is changed by the same amount, if the deviation is large, The feedback control amount also increases, and the gear shifting speed increases.
Conversely, when the rotational speed deviation is small, the feedback control amount becomes small and the shifting speed becomes low, so that the control gain during shifting becomes substantially different, resulting in a difference in the shifting speed. As a result, the shift responsiveness differs for each shift, causing problems in good drivability of the vehicle.

The present invention has been made in view of the above points, and its purpose is to always maintain the speed change ratio regardless of the rotational speed of the driving pulley or the driven pulley at the time of changing the gear ratio. The objective is to control the speed change to the same speed.

(Means for Solving the Problem) In order to achieve the above object, in the present invention, when changing the gear ratio by the same amount of change, the rotation speed of the driving pulley and the rotation speed of the driven pulley at the time of the change are If they are different, the rotational speed deviation will also be different, but the feedback control amounts calculated based on the rotational speed deviation and the control gain are set to be equal to each other.

In other words, the specific solution of the present invention includes a driving pulley and a driven pulley configured to have variable effective radii, a belt wound between the two pulleys, and a variable effective radius of the driving pulley and driven pulley. The object of this invention is a continuously variable transmission equipped with an adjusting means for adjusting the speed. and target rotation speed setting means for setting a target rotation speed of the drive pulley corresponding to a target speed ratio according to the operating state, rotation speed detection means for detecting the actual rotation speed of the drive pulley, and the target rotation speed. a control means that receives the outputs of the setting means and the rotation speed detection means and performs feedback control on the adjustment means so that the rotation speed of the drive pulley becomes the target rotation speed based on the deviation between the target rotation speed of the drive pulley and the actual rotation speed; will be established. Further, a control gain changing means is provided for changing the control gain of the control means in accordance with the magnitude of the deviation between the target rotational speed and the actual rotational speed of the drive pulley when changing the gear ratio.

(Function) With the above configuration, in the present invention, the gear ratio can be changed to the 10th gear ratio, for example.
In the case of changing from 0.5 to 0.7 in the figure, when shifting at point A in the figure, the control gain is changed to a small value by the control gain changing means, although the rotational speed deviation is large. On the other hand, when shifting at point B in the figure, the rotational speed deviation is smaller than at point A, so the control gain is changed significantly by the control gain changing means. As a result, at points A and B in the figure,
Since the values of the feedback control amount obtained by multiplying the rotation speed deviation and the control gain are equal to each other, even if the rotation speed deviation is different, the actual control gain becomes the same and the speed of change of the gear ratio can be controlled. Can be made the same.

Moreover, even when the rotational speed deviation is large, the feedback control amount is an appropriate value and does not become too large, so hunting, where the rotational speed of the drive pulley fluctuates around the target rotational speed, can be effectively prevented.

In the above case, the magnitude of the control gain was changed directly according to the magnitude of the rotation speed deviation, but the rotation speed deviation was
As can be seen from Figure 0, it changes depending on the target rotation speed and actual rotation speed of the driving pulley, and the actual rotation speed of the driven pulley. The magnitude of the control gain may be changed depending on the number.

(Effects of the Invention) As explained above, according to the shift control device for a continuously variable transmission of the present invention, when controlling the gear ratio to the target gear ratio, the rotation speed of the drive pulley and its target rotation speed are In the configuration where the deviation is calculated and the rotation speed of the drive pulley is feedback-controlled to the target rotation speed based on this deviation, the deviation of the rotation speed of the drive pulley from the target rotation speed is different when changing the gear ratio. However, since the substantial control gains can be made equal, the gears can always be shifted at the same shifting speed, and good shifting characteristics can be obtained. Furthermore, it is possible to prevent the rotational speed of the drive pulley from hunting around the target rotational speed.

(Example) Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows the overall structure of a continuously variable transmission. The continuously variable transmission shown in the figure includes a torque converter 2 connected to an output shaft 11 of an engine 1, a forward/reverse switching mechanism 3, a continuously variable transmission mechanism 4,
It basically consists of a speed reduction mechanism 5 and a differential mechanism 6.

The torque converter 2 includes a pump cover 21 coupled to the engine output shaft 11, a pump impeller 22 fixed to one side of the pump cover 21 and rotating integrally with the engine output shaft 11, and the pump impeller 22. a turbine runner 23 rotatably provided inside the pump cover 21 so as to face the turbine launch 23;
The stator 24 is interposed between the pump impeller 22 and the pump impeller 22 to increase torque, and the turbine shaft 25 is fixed to the turbine runner 23. The stator 24
is connected to the transmission case 7 via a one-way clutch 26 and a stator shaft 27. A turbine shaft 2 is provided between the turbine launch 23 and the pump cover 21.
A lock-up piston 28 is slidably attached to the lock-up piston 28, and hydraulic pressure is introduced into and discharged from a lock-up engagement chamber 29g and a lock-up opening chamber 29b formed on both sides of the lock-up piston 28. The piston 28 and the pump cover 21 are connected and opened.

The forward/reverse switching mechanism 3 includes a carrier 31, a pinion gear 32°32 supported by the carrier 31, a sun gear 34 spline-coupled to a primary shaft 411 of a continuously variable transmission mechanism 4 (described later) and meshing with the pinion gear 32, and a pinion gear 32, and the ring gear 35 is spline-coupled to the turbine shaft 25 of the torque converter 2. Further, a forward clutch 36 is provided between the ring gear 35 and the carrier 31 to connect and disconnect them, and a forward clutch 36 is provided between the carrier 31 and the transmission case 7 to selectively fix the carrier 31 to the transmission case 7. A reverse brake 37 is provided. With this configuration, when the forward clutch 36 is engaged and the reverse brake 37 is released, the ring gear 3
5 and the carrier 31 are connected to rotate integrally, and the rotation of the turbine shaft 25 is directly transmitted to the primary shaft 4 of the continuously variable transmission mechanism 4.
On the other hand, when the reverse brake 37 is engaged and the forward clutch 36 is released, the carrier 31 is fixed non-rotatably to the case 7, and the rotation of the ring gear 35 is transmitted to the sun gear 34 via the pinion gear 32... The rotation of the turbine shaft 25 is reversed and transmitted to the primary shaft 411 of the continuously variable transmission mechanism 4. Further, when both the forward clutch 36 and the reverse brake 37 are released, the continuously variable transmission mechanism 4 is connected to the turbine shaft 25.
(in neutral and parking states), the driving force of the engine is no longer transmitted to the primary shaft 411 of the vehicle.

The continuously variable transmission mechanism 4 includes a primary pulley 41 as a driving pulley, a secondary pulley IJ42 as a driven pulley, and a V-belt 43 wound between these pulleys 41 and 42.

The primary pulley 41 includes a primary shaft 411 disposed coaxially with the turbine shaft 25, a fixed conical plate 412 fixed to the primary shaft 411, and a fixed conical plate 412 disposed opposite to the fixed conical plate 412 and attached to the primary shaft 411. It has a movable conical plate 413 that is slidably supported. Then, when the movable conical plate 413 moves, the gripping position of the belt 43 changes, and the effective pitch diameter (effective radius)
is starting to change. That is, the movable conical plate 4
13 approaches the fixed conical plate 412, the effective pitch diameter increases, and the movable conical plate 413 moves closer to the fixed conical plate 412.
When the pitch moves away from the pitch, the effective pitch diameter becomes smaller.

Further, the secondary pulley 42 basically has the same configuration as the primary pulley 41 described above.

That is, it has a secondary shaft 421 arranged parallel to the primary shaft 411, a fixed conical plate 422 fixed to the secondary shaft 421, and a movable conical plate 423 slidably supported. The effective pitch diameter is changed.

Each movable conical plate 413 in each of these pulleys 41, 42
, 423 are provided with movable conical plates 413, 4, respectively.
Hydraulic cylinders 414, 424 for sliding 23 are provided. The pressure receiving area of the hydraulic cylinder 414 of the primary pulley 41 is set to about twice the pressure receiving area of the hydraulic cylinder 424 of the secondary pulley 42.

Hydraulic pressure is introduced and discharged into the hydraulic cylinder 414 of the primary pulley 41 in order to change the gear ratio between both pulleys 41 and 42, and the hydraulic cylinder 424 of the secondary pulley 42 always maintains the appropriate tension of the V-belt 43. Hydraulic pressure is introduced and discharged to maintain the And the hydraulic cylinder 41 of the primary pulley 41
When hydraulic pressure is introduced into the primary pulley 41, the position where the V belt 43 is held in the primary pulley 41 moves outward, and the effective pitch diameter of the primary pulley 41 increases.
Along with this, the V belt 4 at the secondary pulley 42
3 moves inward, the effective pitch diameter of the secondary pulley 42 becomes smaller, and the gear ratio between the primary shaft 411 and the secondary shaft 421 changes to a smaller value (in the direction of speed increase). Conversely, when hydraulic pressure is discharged from the hydraulic cylinder 414, the effective pitch diameter of the primary pulley 41 becomes smaller and the effective pitch diameter of the secondary pulley 42 becomes larger, resulting in a change in the gear ratio between the primary shaft 411 and the secondary shaft 421. changes significantly (in the direction of deceleration).

Further, the speed reduction mechanism 5 and the differential mechanism 6 have a known structure, and are adapted to transmit the rotation of the secondary shaft 421 to the axle shaft 61.

Next, the torque converter 2 in the above-mentioned continuously variable transmission
, the forward clutch 36 and reverse brake 37 of the forward/reverse switching mechanism 3, and the primary pulley 41 and secondary pulley 4 of the continuously variable transmission mechanism 4.
The hydraulic circuit that controls each operation of the 2 and 2 will be explained based on FIG. 2.

The hydraulic circuit shown in the figure includes an oil pump 81 driven by the engine 1. The hydraulic oil discharged from the oil pump 81 is first adjusted to a predetermined line pressure by the line pressure regulating valve 82 and then supplied to the hydraulic cylinder 424 of the secondary pulley 42 via the line 101. Finally, the hydraulic cylinder 4 of the primary pulley 41 is connected to the hydraulic cylinder 4 of the primary pulley 41 via a line 102 branched from the
14.

The line pressure regulating valve 82 has a spool 8 composed of a main spool 821 and a sub spool 822 arranged in series.
It has 20. A main spool 821 and a sub-spool 822 constituting the spool 820 are connected such that one end of the sub-spool 822 is brought into contact with one end of the main spool 821. At the other end of the sub spool 822,
A large diameter portion 822a is provided which has a larger cross-sectional area than the contact area (cross-sectional area of the connecting portion) with the main spool 821. At a position corresponding to the center of the main spool 821 is a pressure regulating boat 82 to which oil discharged from the oil pump 81 is guided.
3 and a drain boat 824 that communicates with the suction side of the oil pump 81. When the main spool 821 moves to the left side in the figure, a pressure regulating boat 823 and a drain boat 824 are provided.
When the main spool 821 moves to the right side in the figure, the pressure regulating boat 823 and the drain boat 824 are cut off, and when the main spool 821 moves to the right side in the figure, the pressure regulating boat 823 and the drain boat 824 are cut off. 824 are communicated with each other. A first pilot chamber 825 is located at a position corresponding to the connecting portion between the main spool 821 and the sub spool 822.
A spring 826 is interposed in the first pilot chamber 825 to urge the main spool 821 to the left in the figure. In addition, the large diameter portion 822 of the sub spool 822
A second pilot chamber 827 communicating with the first pilot chamber 825 is formed in a. These first pilot chamber 825 and second pilot chamber 827 have a line 10
2, the hydraulic oil is reduced to a predetermined pressure by the reducing valve 83 while passing through the line 103, and is introduced as a pilot pressure adjusted by the first duty solenoid valve 91 while passing through the pilot passage 103a. It has become so. While this pilot pressure acts in the same direction as the biasing force of the spring 826,
The hydraulic pressure in the line 101 acts on the other end of the main spool 821 to counteract the biasing force and pilot pressure, and the spool 820 moves due to the force relationship between the pressure regulating boat 823 and the drain boat 824. By communicating and cutting off the line pressure, the line pressure is controlled to a value corresponding to the pilot pressure regulated by the first duty solenoid valve 91.

A speed ratio control valve 85 is provided in the line 102 . The gear ratio control valve 85 includes a spool 851 and a spring 8 that urges the spool 851 to the right in the figure.
52, a line pressure boat 853 connected to the upstream part of the line 102, a drain boat 854, and a spring 85.
2. A reverse boat 855 opened on the installation side and connected to the shift valve 87 via the line 104, and a spring 852.
It has a pilot chamber 856 formed on the opposite side to the installation side and into which pilot pressure is introduced. Pilot room 856
is connected via a pitot valve 86 to a second duty solenoid valve 92 and a pitot pressure generating means 90 that generates a pitot pressure corresponding to the rotation speed of the engine 1. Therefore, the pitot pressure generated by the pitot pressure generating means 90 and the pressure adjusted by the second duty solenoid valve 92 can be selectively introduced into the pilot chamber 856 as pilot pressure by the pitot valve 86,
Even if the second duty solenoid valve 92 fails, the pitot pressure generating means 90 can
Pitot pressure can be introduced as pilot pressure.

When the gear ratio control valve 85 is moving forward (when the shift valve 87 is in any of the shift positions 2.1), hydraulic pressure is drained from the reverse boat 855 through the shift valve 87. Therefore, the spool 851 moves due to the force relationship between the pilot pressure introduced into the pilot chamber 856 and the biasing force of the spring 852, and the line pressure port 8
53 and the drain boat 854 are selectively communicated with the hydraulic cylinder 414 of the primary pulley 41.

In this way, when moving forward, the pilot chamber 856
Primary pulley 4
The adjustment means 100 is configured to variably adjust the effective radius of the primary pulley 41 and the secondary pulley 42 of the continuously variable transmission mechanism 4 by controlling the supply and discharge of hydraulic pressure to the hydraulic cylinder 414 of 1. .

On the other hand, when moving backward (when the shift valve 87 is in the R shift position), hydraulic pressure (operating pressure to be described later) from the reverse boat 855 is introduced, and this positive operation causes the spool 851 to
is fixed in a state where it is pressed to the right side in the figure. Therefore, when the vehicle moves backward, the hydraulic cylinder 414 of the primary pulley 41 and the drain boat 854 are constantly communicated with each other, and the gear ratio is fixedly maintained at the maximum gear ratio.

In addition, even in neutral and parking (when the shift valve 87 is in each of the N and P shift positions), where the driving force of the engine 1 is not transmitted to the axle 61 by the forward/reverse switching mechanism 3, the same state as in reverse occurs. .

The hydraulic oil whose pressure is regulated by the line pressure regulating valve 82 is
In addition to line 101, it is also sent out to line 105. The hydraulic fluid sent to the line 105 is adjusted to a predetermined operating pressure by the operating pressure regulating valve 88 and then supplied to the lines 106 and 107.

The operating pressure regulating valve 88 has a spool 881 and a spool 88.
a pilot chamber 882 formed on one end side of 1; a spring 883 interposed in this pilot chamber 882;
It has a first pressure regulating boat 884 connected to the line 105, a second pressure regulating boat 885 connected to the line 107, and a drain boat 886. Pilot chamber 882 is connected to first duty solenoid valve 91 via pilot passage 103a. Therefore, the pilot chamber 882 includes the first duty solenoid valve 9.
The hydraulic oil whose pressure was regulated in step 1 is introduced as pilot pressure. This pilot pressure acts in the same direction as the biasing force of the spring 883, while the spool 888 acts in the same direction as the biasing force of the spring 883.
The hydraulic pressure in the line 105 acts on the other end of the spool 881, and the spool 881 moves due to the force relationship between the first and second spools.
By communicating and disconnecting between the E pressure boats 884 and 885 and the drain boat 886, the operating pressure of the forward clutch 36 and reverse brake 37 becomes the pilot pressure regulated by the first duty solenoid valve 91. The value is controlled accordingly.

The hydraulic oil supplied to the line 106 is transferred to the shift valve 87
Gari, 2. When in the shift position 1, the forward clutch 3 of the forward/reverse switching mechanism 3 is connected via the line 109.
6, and when the shift valve 87 is in the R shift position, it is supplied to the hydraulic chamber 37a of the reverse brake 37 of the forward/reverse switching mechanism 3 via line 108, and also via line 104 for gear change. It is supplied to a reverse boat 855 of the ratio control valve 85. On the other hand, the hydraulic fluid in each hydraulic chamber 36 a T 37 a of the forward clutch 36 and reverse brake 37 of the forward/reverse switching mechanism 3 flows through the line 109, when the shift valve 87 is in the R, N, or P shift position. It is designed to be discharged through 108. Therefore, the forward clutch 36 and the reverse brake 37 of the forward/reverse switching mechanism 3 are engaged and opened according to the shift position of the shift valve 87, and as described above, the shift position RlN and P are stepless. The gear ratio of the transmission mechanism 4 is held fixed at the maximum gear ratio.

Further, the hydraulic oil supplied to the line 107 is supplied to the torque converter 2 through the lock-up control valve 89.
It is supplied to the lockup closing chamber 2gB or the lockup opening chamber 29b. The lock-up control valve 89 is configured such that the operation of the spool 891 is controlled by the pilot pressure regulated by the third duty solenoid valve 93. Then, when the pilot pressure becomes lower, the spool 891 moves to the right in the figure and connects the line 107 to the lockup fastening chamber 29.
As hydraulic oil is supplied to the lock-up opening chamber 29b, and the pilot pressure increases, the spool 891 moves to the left in the figure, and the hydraulic oil in the lock-up opening chamber 29b begins to drain. The hydraulic oil is supplied to the lockup opening chamber 29b, and the hydraulic oil in the lockup engagement chamber 29a is drained.

Note that 94 indicates that the first duty solenoid valve 91 is O.
An accumulator valve is used to prevent the pilot pressure in the pilot passage 103a from pulsating when the N/OFF state is turned off, 95 and 96 are accumulators that cushion the shock when the forward clutch 36 and reverse brake 37 are engaged, respectively, and 97 is a relief. It's a valve. Further, 98 is a pressure holding valve that maintains a predetermined low constant pressure when draining the pressure oil in the hydraulic cylinder 414 of the primary pulley 41.

FIG. 3 shows the electric control circuit of the above-mentioned continuously variable transmission. In this figure, a control unit 110 containing a microcomputer etc. receives a shift position signal from a shift position sensor 111 that detects the shift position (D, 1, 2 degrees R, N, P) operated by the driver. A primary pulley rotation speed signal from a primary rotation speed sensor 112 as a rotation speed detection means that detects the actual rotation speed of the primary pulley 41, that is, the rotation speed np of the primary shaft 411, and a secondary pulley rotation speed signal that detects the rotation speed ns of the secondary shaft 421. Secondary pulley rotation speed signal from rotation speed sensor 113 and throttle valve opening degree TV of engine 1
The throttle valve opening signal from the throttle opening sensor 114 that detects O, the engine rotational speed signal from the engine rotational speed sensor 115 that detects the rotational speed Ne of the engine 1, and the turbine rotation of the turbine shaft 25 of the torque converter 2. A turbine rotation speed signal from a turbine rotation speed sensor 116 that detects the number Nt is input.

The control unit 110 performs duty control on the first to third duty solenoid valves 91, 92, and 93 based on these input signals, thereby controlling the line pressure regulating valve 82, the operating pressure regulating valve 88, and the gear ratio. control valve 8
5 and the lock-up control valve 89 are adjusted.

Next, gear ratio control by the control unit 110 will be explained based on the control flow shown in FIG. 4.

Start and set the primary rotation speed np at step SA+
1 Secondary rotation speed ns and throttle valve opening TVO
After reading, in step SA2, the eighth
From the map shown in the figure, the target rotation speed (target primary rotation speed) of the primary pulley 41 corresponding to the target gear ratio npo
At the same time, the deviation Δn(-"p npo) between the actual primary rotation speed np and the target primary rotation speed npo read in step SA3 is calculated.

In step SA4, the control gain correction term kc is calculated using the primary rotational speed np when calculating this correction term.
+, and calculate using the formula k c-n p 1 / npo.

After that, in step SAS, the integral term C1nts, the proportional term Cprp, and the differential term Cde are used as feedback control variables.
f, its integral gain ki1, proportional gain kp, differential gain kd, current and previous rotation speed deviation Δni,
It is calculated by the following formula based on Δn1-1% and the correction term kc of the control gain.

Finally, in step SA6, each of the above correction terms C1n
t, Cprp, and Cdef' is converted into a control duty rate for the second duty solenoid valve 92 for the gear ratio control valve 85, and this control duty rate signal is used to control the second duty solenoid valve. 92 and ends.

Therefore, in the speed ratio control flow shown in FIG. 4, in step S^2, the [1 standard rotation speed] of the primary pulley 41 corresponding to the target speed ratio according to the operating state determined from the throttle valve opening TVO and the secondary rotation speed ns is determined. A target rotation speed setting means 150 is configured to set npo. Further, in steps SA3, S^5, and SA6 of the same control flow, the outputs of the target rotation speed setting means 150 and the primary rotation speed sensor 112 are received, and the deviation between the target rotation speed npo and the actual rotation speed np of the primary pulley 41 is determined. Primary pulley 4 based on Δn(”np npo)
1 rotation speed np is the target rotation speed np. The control means 151 is configured to perform feedback control on the second duty solenoid valve 92 for the gear ratio control valve 85 of the adjustment means 100 so as to achieve the following. Furthermore, in steps SA4 and SA5 of the same control flow, if the amount of change in the gear ratio is the same, as can be seen from the shift map in FIG. 10, the target primary rotation speed npo when changing the gear ratio
The higher the rotation speed npQ is, the larger the deviation Δn between the target rotation speed npQ and the actual rotation speed np becomes. The control gain changing means 152 is configured to change each control gain of the integral gain ki, the proportional gain tcp, and the differential gain kd of the control means 151 smaller in inverse proportion to the larger value.

Therefore, in the above embodiment, when changing the gear ratio from 0.5 to 0.7 at points A and B in FIG. 10, for example, the rotation speed deviation Δn(-np-npo) at point A. is large and small at point B.

However, the correction term kc of the feedback control gain is inversely proportional to the target primary rotational speed npo.
Since o is set to a smaller value as o becomes higher, the correction term kcO value at point A on the higher side of target primary rotation speed npo is:
It becomes smaller than the value at point B on the lower side of the target primary rotation speed npo.

As a result, the feedback control amounts found by multiplying the rotational speed deviation Δn by the correction term kc have the same value, so when changing the gear ratio by the same amount of change, the target primary rotational speed np at that time The speed change speeds can be made the same regardless of the speed.

Moreover, at point A, although the rotational speed deviation Δn is large, the integral, proportional, and differential control gains ki, kp, and kd are multiplied and corrected by the correction term kc and become small, so that the feedback control amount becomes an appropriate value. , the primary rotational speed np can be smoothly shifted without hunting when converging to the target rotational speed npo.

Above, we have explained the case where the gear ratio is changed from 0.5 to 0.7, but in addition, when changing the gear ratio from 1.8 to 2, or 0, etc., the same gear shifting speed as the above gear changing is used. Obtainable.

FIG. 5 shows the calculation of the control gain correction term kc based on both the primary rotational speed np and the secondary rotational speed ns. In other words, the gear ratio control flow in the same figure differs from the above-mentioned figure 4 only in step SB4, and this step S
In B4, as shown in FIG. 6, the higher the primary rotation speed np is, the smaller the primary correction term kc is set, and
As shown in FIG. 7, the higher the secondary rotation speed ns is, the smaller the secondary correction term kc2 is set, and the result of multiplying both correction terms kc, , kc2 is set as the correction term kc. The calculation of this correction term kc is based on the map shown in FIG.
It may be set smaller as s becomes higher.

Therefore, in this embodiment, the control gain correction term kc changes depending on the secondary rotation speed ns in addition to the primary rotation speed np, and is set smaller as the secondary rotation speed ns is higher (vehicle speed is higher). Due to this, the 10th
When changing the gear ratio from 0.5 to 0.7 at point A in the figure, and when changing the gear ratio from 1.8 to 2.0 at point C in the figure, the primary rotational speed np The rotation speed is the same in the 2500 r, p, and layers, but the rotation speed deviation ΔN is large at point A (
, Although it is small at point 0, the correction term kc is set to a small value at point A as the secondary rotation speed ns is lower than at point 0, so the amount of phytback control is the same value at point A and point 0. As a result, the shifting speeds become the same.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention, in which Fig. 1 is an overall schematic diagram of a continuously variable transmission, Fig. 2 is a hydraulic control circuit diagram, Fig. 3 is a block diagram of an electrical control system, and Figs. 4 and 5. The figure is a flowchart showing the gear ratio control, Figures 6 and 7 are diagrams showing the characteristics of the correction term of the feedback control gain for the primary rotation speed and the secondary rotation speed, respectively, and Figure 8 shows the target primary rotation speed characteristics. 9 and 9 are diagrams showing a map of the correction term of the feedback control gain, and FIG. 10 is a diagram showing a shift map. 41...Primary brake (drive pulley) 42...
Secondary pulley (driven pulley), 43...belt,
85... Gear ratio control valve, 100... Adjustment means, 11
2. Primary rotation speed sensor (rotation speed detection means),
150... Target rotation speed setting means, 151... Control means, 152... Control gain changing means. Other 2 people 4 Figure Ara 1 Mari [ ] Number of sheets P Auction times f yun number ns Figure Figure Auction) Tapariro number of houses ns Figure 381- Figure Figure

Claims (4)

[Claims] (1) A drive pulley and a driven pulley configured to change the effective radius, a belt wound between the two pulleys, and an adjusting means for variably adjusting the effective radius of the drive pulley and the driven pulley. In the continuously variable transmission, target rotation speed setting means for setting a target rotation speed of the drive pulley corresponding to a target speed ratio according to the operating state; rotation speed detection means for detecting the actual rotation speed of the drive pulley; In response to the outputs of the target rotation speed setting means and rotation speed detection means, the adjustment means is feedback-controlled to adjust the rotation speed of the drive pulley to the target rotation speed based on the deviation between the target rotation speed and the actual rotation speed of the drive pulley. and a control means for
A continuously variable transmission characterized by comprising a control gain changing means for changing the control gain of the control means according to the magnitude of the deviation between the target rotational speed and the actual rotational speed of the drive pulley when changing the gear ratio. Machine speed control device. (2) The speed change control device for a continuously variable transmission according to claim (1), wherein the control gain changing means changes the control gain of the control means in accordance with the rotational speed of the drive pulley. (3) The speed change control device for a continuously variable transmission according to claim (1), wherein the control gain changing means changes the control gain of the control means in accordance with the rotation speed of the driven pulley. (4) The speed change control device for a continuously variable transmission according to claim (1), wherein the control gain changing means changes the control gain of the control means in inverse proportion to the rotation speed of the driving pulley or the rotation speed of the driven pulley. .